Refresh ikiwiki wrappers when ikiwiki.setup.erb is updated

Originally created by @intrigeri on #16542 (Redmine)

As seen on https://gitlab.tails.boum.org/tails/tails/-/issues/16483#note_8436, some changes to ikiwiki.setup deployed via Puppet (templates/website/ikiwiki.setup.erb) are not fully applied until a sysadmin manually runs ikiwiki with the --wrappers option. Like any “after X one must do Y by hand”, even if that was documented, we’re bound to forget it occasionally. Let’s instead teach Puppet to do that itself automatically :)

Related issues

• Related to tails/tails#16483
• Related to tails/sysadmin#14588